The invention relates to exercise and sports, in particular to applications in which human energy consumption is measured in connection with exercise.
To determine energy consumption in connection with exercise is important when planning a correct relation between an athlete""s nutrition and intensity of exercise. An exercise of excessive duration, for instance, may deplete the person""s energy reserves to a disadvantageous level. Further, if the objective is to lose weight, it is important to obtain information on the amount of energy consumed during exercise.
Intensity of a workout or exercise can be described by means of the person""s heart rate. The heart rate represents the heart beat frequency in a time unit, the unit being e.g. beats per minute. Sports and exercise increase the heart muscle mass and the capability of the system to supply oxygen to the body. The heart""s capability to pump oxygenated blood into the body improves, and consequently by one contraction, i.e. beat, the heart is able to pump a larger amount of blood in the body, whereby the beat rate can be lower than that of an unfit person. The person""s heart rate during exercise is measured with a heart rate monitor, for instance. The heart rate monitor is a device that measures heart rate, for instance, on the chest from an electric signal transmitted by the heart and displays the measured heart rate on its display. The heart rate monitors often comprise a plurality of other facilities apart from the heart rate measurement, such as assessment of energy consumption during exercise. In prior art heart rate monitors energy consumption has been assessed on the basis of the heart rate and the person""s weight, gender and age, for instance.
Hence, it is clear that the prior art heart rate monitors assessing energy consumption have a significant disadvantage. The method does not take into account that a fit person performs a larger amount of work at a given heart rate level than an unfit person, whereby the amount of energy consumed by the fit person is larger than that of the unfit person.
The object of the invention is to provide an improved method and equipment implementing the method for assessing energy consumption during exercise. This is achieved by the method described below. This is a method for assessing a person""s energy consumption during exercise. The method provides an assessment of the person""s energy consumption by means of at least two calculating parameters, one of which is a heart rate parameter during exercise measured from the person""s heart rate information. As one calculating parameter the method employs an energy consumption reference value which is obtained by using one or more performance parameters representing the person""s physical performance.
The invention also relates to a heart rate measuring arrangement comprising measuring means for measuring a person""s heart rate during exercise and a calculating unit for calculating an assessment of the person""s energy consumption during exercise using at least two calculating parameters, one of which is a heart rate parameter included in the person""s measured heart rate information, the heart rate measuring arrangement further comprising presenting means for presenting the formed assessment of the person""s energy consumption. The calculating unit is arranged to use an energy consumption reference value as a calculating parameter, which reference value is obtained by using one or more performance parameters representing the person""s physical performance.
The preferred embodiments of the invention are disclosed in the dependent claims.
The invention thus relates to a method and equipment for assessing a person""s energy consumption during exercise. In the description of the invention, the exercise refers to a physical exercise that is performed at a higher heart rate level than the resting heart rate. Broadly speaking, the invention relates to assessing human energy consumption as the heart rate level exceeds 80 beats per minute.
According to the method of one preferred embodiment of the invention, equipment implementing the method, such as a heart rate monitor, is personally set for each performer of exercise in a personalizing phase of the method. The personalizing phase is preferably performed prior to the exercise and in that step an assessment is made of the person""s physical condition, which assessment is utilized in assessing the energy consumption on the basis of the heart rate information during the exercise. An advantage with this is that it takes into account the fact that at a given heart rate level a fit person consumes more energy than an unfit person. The physical condition is described by the maximum performance parameter value, such as the maximal oxygen uptake value, maximum value of running or swimming speed, maximum performance when pedalling an exercise bike or the like.
In one preferred embodiment of the invention, interdependence between the person""s heart rate and energy consumption is determined in a personalizing phase by means of a performance parameter, such as oxygen uptake. First, a maximum value of oxygen uptake is formed at an upper heart rate level, which preferably is the maximum heart rate level corresponding to the person""s maximum performance. On the basis of the formed maximum value of oxygen uptake it is possible to form a maximum value of energy consumption representing the person""s maximal energy consumption in accordance with the known principles of human physiology. The upper heart rate level allows to form a lower heart rate level, whose lower energy consumption is correspondingly formed by means of the maximum energy consumption. Between the formed upper heart rate level and the lower heart rate level, there is substantially linear dependence between the heart rate and the energy consumption.
According to another preferred embodiment, an intermediate heart rate level is designated between the lower heart rate level and the upper heart rate level, whereby the interdependence of the heart rate and the energy consumption is piecewise linear comprising linear interdependences between the lower and intermediate heart rate levels and the intermediate and upper heart rate levels respectively. The use of intermediate heart rate level allows to precise the actual energy consumption values. It is clear that the method of the invention may comprise a plurality of intermediate heart rate levels. It is clear that the physiological dependence between the heart rate and the energy consumption is not an exact linear dependence. In the above-described embodiments the expression substantially linear refers to dependences that are within a 10% range of variation in either direction with respect to the linear dependence, being e.g. piecewise linear or curve forms of higher degree.
The upper heart rate level to be used in forming the maximum value of the performance parameter is preferably the maximum heart rate level that can be generated, for instance, by assessing, calculating by a formula (220xe2x88x92age), measuring the heart rate corresponding to the maximum workload, or by forming an assessment of the maximum heart rate level by means of a neural network model, into which at least one physiological parameter of the person, such as age, weight, height, gender or the like, is entered as an input parameter.
The maximum value of the performance parameter corresponding to the upper heart rate level is formed, for instance, by measuring during exercise stress or by means of a neural network model. In one preferred embodiment of the invention, the neural network model is such that one or more heart rate parameters obtained from heart rate information, one or more physiological parameters and one or more exercise stress parameters are entered therein as input parameters. In one embodiment of the invention, a reference exercise is performed in the personalizing phase, the above exercise stress parameters then referring to parameters representing the workload of the reference exercise, such as resistance of an exercise bike, swimming speed, running speed or the like. On the basis of the known physiological formulae determining the interdependence of breathing gases and energy consumption it is possible to calculate the energy consumption value corresponding to the maximum value of the performance parameter, whereby the dependence between the heart rate and the energy consumption at the upper heart rate level is obtained. If a variable representing performance or speed is used as the performance parameter, the energy consumption is given by a formula having the structure: performance/speed * weight * constant, the constant determining the person""s efficiency in exercise, for instance.
The lower heart rate level is formed from the upper heart rate level, for instance, by calculating about 50 to 60% of the maximum heart rate level. The lower heart rate level is selected such that the dependence between the heart rate and the energy consumption is known at heart rate levels exceeding the lower level, i.e. the dependence is linear or at least piecewise linear. The energy consumption corresponding to the lower heart rate level is obtained from the maximum energy consumption corresponding to the maximum heart rate, for instance, by calculating about 40% of the maximum energy consumption. If one intermediate heart rate level is used, the intermediate heart rate level is about 80% of the maximum heart rate and the energy consumption is about 75% of the maximum energy consumption.
In the use phase of the method, i.e. during an exercise, an assessment of energy consumption is formed by means of at least two calculating parameters. One of the calculating parameters is the person""s heart rate during exercise. Instead of or in addition to the heart rate, it is also possible to use any other heart rate variable describing the workload of the performance, such as the standard deviation of the heart rate. In assessing energy consumption, one calculating parameter is one or more energy consumption reference values, such as maximum energy consumption, lower energy consumption, intermediate energy consumption, generated in the personalizing phase. Further, one embodiment employs one or more of the following variables as a calculating parameter: upper heart rate level, lower heart rate level, intermediate level.
In one embodiment of the invention equipment implementing the method of the invention is a heart rate monitor. The heart rate monitor is a device employed in sports, which measures human heart rate information either from an electrical impulse transmitted by the heart or from the pressure produced by the heart beat on an artery, or optically from blood flow in a blood vessel. Heart rate monitors have a variety of different structures, but the invention is not restricted to any particular heart rate monitor type. For instance, the heart rate monitor can be such that it comprises an electrode belt to be fitted around the user""s chest measuring the heart rate by means of two or more electrodes. The electrode belt transmits the measured heart rate information inductively to a wrist-worn receiver unit. On the basis of the received magnetic pulses, the receiver unit calculates the heart rate and, when needed, other heart rate variables, such as moving standard deviation of the heart rate. The receiver unit, i.e. the wrist monitor, often includes a display for displaying the heart rate information or other parameters generated in the heart rate monitor. In connection with the present invention, variables, such as cumulative consumed energy or consumed energy per time unit, representing energy consumption during exercise are preferably presented on the display. Advantageously, the heart rate monitor also comprises means for entering user-specific physiological information as well as workload and exercise information. The entering means can be, for instance, a keypad of the heart rate monitor, display equipment that supports control, speech control, a telecommunication port for external control, or the like. In the above-described situation, the heart rate monitor refers to a whole formed by the electrode belt and the receiver unit.
The heart rate monitor can also be a one-piece device, i.e. such that also the presenting means are located on the chest, whereby there is no need to transmit the information to a separate receiver unit. Further, the structure of the heart rate monitor can be such that it comprises only a wrist-worn monitor which operates without the electrode belt to be fitted around the chest measuring the heart rate information from the vessel pressure or optically. In the description of the invention, the heart rate measuring arrangement refers to the above-described heart rate monitor solutions. The heart rate measuring arrangement also comprises the solutions, in which heart rate information is transmitted to an external computer or to a data network, which has presenting means, such as a computer screen, for presenting the information measured or generated by the heart rate monitor. In one embodiment the heart rate and energy consumption information during exercise is stored in a memory of the heart rate monitor and downloaded later on by an external computer.
In the case of a two-piece heart rate monitor the functions required by the method of the invention are preferably performed in the receiver unit. One or more mathematical models, such as a neural network, according to the invention and other functions required by the models are preferably implemented by means of software for a general-purpose processor of the receiver unit. The models and the functions can also be implemented as ASIC, by separate logic components or in any other corresponding manner.
An improved method for assessing energy consumption during exercise is achieved as an advantage of the invention. The method has an advantage that in the assessment of energy consumption the person""s physical condition is taken into account. A further advantage is that the person""s maximum heart rate and the corresponding energy consumption value are taken into account.